Amines from alcohols

ABSTRACT

Mono- and di-lower alkylamines, e.g. methylamine or dimethylamine, are alkylated by reaction with C 8-22  alcohol in the presence of hydrogen at a temperature of about 150°-275° C. in contact with a copper-zinc-alkaline earth metal base containing catalyst (e.g., CuO-ZnO-Ba(OH) 2 ) while removing water formed in the reaction.

This application is a continuation-in-part of applications Ser. No.022,095 and Ser. No. 022,047 both filed Mar. 5, 1987 both now abandonedand Ser. No. 079,522 filed July 30, 1987 now abandoned.

BACKGROUND

It has long been known that alcohol can react with ammonia or primary orsecondary amines to replace one or more hydrogen atoms bonded tonitrogen with the alkyl residue of the alcohol. The reaction is promotedby catalysts. Use of a supported oxygen compound of phosphorus isreported in U.S. Pat. No. 2,073,671. Another process is described inU.S. Pat. No. 2,160,058 using copper-barium-chromium oxides,copper-chromium oxides or copper-aluminum oxides. Reaction of ethyleneglycol with ammonia using a catalyst such as nickel-aluminum,nickel-silicon, nickel, copper, copper-chromium, copper-zinc-chromium,thorium, magnesium, molybdenum or osmium oxides is said to form alkoxyamines according to U.S. Pat. No. 2,160,058. Reaction of an alcohol withammonia or an amine in the presence of hydrogen using an alumina orsilica supported cobalt-nickel-copper-catalyst is described in U.S. Pat.No. 4,014,933. Hoshino et al. U.S. Pat. No. 4,210,605 describe a processfor making aliphatic amines by reacting an aliphatic alcohol or aldehydewith ammonia or a primary or secondary amine using a homogenouscolloidal catalyst formed by dissolving a copper or silver salt of afatty acid in alcohol and reducing the metal. Optionally the solutioncan contain a Group VIII metal carboxylate or a manganese or zinc metalcarboxylate. It can also contain an alkali metal or alkaline earth metalcarboxylate. The catalyst formed is a homogenous colloid that cannot beseparated by filtration. In contrast the present catalyst is a solidcatalyst that can be removed by filtration and recycled.

More recently, U.S. Pat. No. 4,409,399 describes the alkylation ofammonia or a primary or secondary amine using as the catalyst anunsupported copper oxide or hydroxide-nickel oxide or hydroxide andoptionally a Group II metal oxide or hydroxide.

One of the problems encountered when making long-chain alkyl di-loweralkylamines such as C₈₁₄ 22 alkyl dimethylamines by the reaction of along-chain alcohol with a di-lower alkylamine is that any unreactedlong-chain alcohol remaining in the reaction mixture will boil at aboutthe same temperature as the desired product which makes purificationvery difficult. Hence, it is essential that conversion of alcohol beessentially complete, e.g., at least 95%, to have a commercially viableprocess when making an amine such as a C₈₋₂₂ alkyl dimethylamine.Likewise it is essential that disproportionation to form long-chainalkylamine and/or long-chain alkyl mono-lower alkylamine be minimized asthese primary and secondary amines are also extremely difficult toseparate from the desired long-chain alkyl di-lower alkylamine product.

SUMMARY OF THE INVENTION

It has now been discovered that both mono- and di-lower alkylamines canbe alkylated in high yields by reaction with an alcohol in the liquidphase and in contact with a supported or unsupported catalyst whichinitially consists essentially of copper or copper oxide, zinc or zincoxide and an alkaline earth metal base. The catalyst can optionallyinclude cobalt, chromium and/or nickel. Introduction of hydrogen duringat least part of the reaction increases the alkylation rate.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the invention is a process for alkylating anamine by reacting a mono- or di-lower alkylamine with an alcohol in theliquid phase at a temperature of about 100°-300° C. and in contact witha non-colloidal catalyst consisting essentially of (1) copper and/orcopper oxide, (2) zinc or zinc oxide and (3) an alkaline earth metalcompound.

The process can be conducted by forming a mixture of the alcohol and analkylamine or dialkylamine containing the catalyst and stirring themixture at reaction temperature, optionally but preferably whilecontacting the mixture with hydrogen. In practice the hydrogen can besparged into the liquid phase and the off-gas, consisting mainly ofhydrogen, passed through a condenser to condense water and othervolatiles which co-distill. The hydrogen can then if desired berecirculated to the reaction mixture. Any amine or alcohol lost in thevent stream can be made-up by adding additional alcohol or amine.

The reaction temperature can vary widely. The temperature should be highenough to cause the reaction to proceed at a reasonable rate but not sohigh as to cause decomposition of reactants or products. A usefultemperature range in which to experiment is about 180°-300° C. Apreferred temperature is 150°-275° C. A more preferred temperature rangeis about 180°-250° C. Excellent results have been achieved in the rangeof 190°-230° C.

The reaction can be conducted at atmospheric pressure or above or belowatmospheric pressure. Best results have been achieved operating atatmospheric pressure. However, if pressure is required to reach thedesired alkylation temperature or to increase the amount of amine in thereaction mixture, then such pressure can be applied. When operatingunder pressure it is still preferred to sparge hydrogen through theliquid phase and to vent the vapor phase through a pressure regulatingvalve.

The ratio of alcohol to amine can vary over a wide range. Stoichiometryfor C₈₋₂₂ alkyl dimethylamine requires one mole of alcohol per each moleof dialkylamine. In practice an excess of amine can be used. Anyunreacted amine can be later removed by distillation. When using ahigher alcohol and a lower dialkyl amine such as dimethylamine, it ispreferred to have the amine in large excess so that all or almost all ofthe alcohol is consumed. This is because the higher alcohols are verydifficult to separate from the higher alkyl di-lower alkylamines. Auseful range is about 1.1-20 moles of di-lower alkylamine per mole ofhigher (e.g. C₈₋₂₂) alcohol. In practice the di-lower alkylamine in thevapor phase, preferably in combination with hydrogen, is continuouslyinjected into the heated liquid reaction mixture. The di-loweralkylamine that does not react with the alcohol can be recovered fromthe vent gas and reinjected until substantially all (e.g., at least 95percent) of the alcohol is converted.

When making a di-(C₈₋₂₂ alkyl) methylamine the ratio of alcohol tomono-alkyl amines should be high enough to dialkylate all or almost allof the initial alkyl amine. An efficient way to conduct the process isto feed mono-alkyl amine until the mole ratio of alcohol to amine feedis about 1.8-2.5:1. The mono-alkyl amine addition can be discontinuedand one can proceed to monitor the reaction composition using gaschromatography (GC) as the reaction proceeds. If it is seen that thealcohol is consumed while substantial amounts of mono- and/or di-alkylamine remain, then more alcohol can be added to convert the mono- and/ordi-alkyl amine to tri-alkyl amine. If on the other hand the amines inthe reaction mixture are all or almost all tri-alkyl amines whileunreacted alcohol remains, then additional mono-alkyl amine can be addedto react with this alcohol. The stoichiometric ratio for the reaction is2 moles of alcohol per mole of alkyl amine but the amount of alcohol andamine actually fed or added to the reaction may vary somewhat from thisideal ratio due to factors such as mono-alkyl amine being lost in thevent gas.

The reaction is conducted for a period of time adequate to achieve thedesired degree of alkylation. The reaction is usually complete in about1-24 hours. A preferred reaction time is about 2-12 hours. Under themost preferred reaction conditions the reaction is essentially completein about 6-10 hours.

The catalyst or mixture of catalysts used in the reaction contains theelements copper, zinc and an alkaline earth metal. The catalyst may besupported or unsupported. Minor amounts of other metals may be presentas long as they do not interfere with the catalytic action of theCu-Zn-alkaline earth metal. The presence of any other catalytic metal isunnecessary. However, the presence of minor amounts of cobalt, chromiumand/or nickel is not considered detrimental.

The copper may be in the form of copper metal, copper oxide or coppercarbonate (e.g. malachite, CuCO₃ Cu(OH)₂). The form in which the copperexists may vary during the reaction due to the environment in which thecatalyst exists. The copper catalyst is preferably added in the form ofcopper oxide. Copper carbonate is believed to form copper oxide in thereaction. Partial reduction to a lower valence or to copper metal mayoccur, especially if the catalyst is contacted with hydrogen beforeand/or during the alkylation. However there is no indication of coppermetal formation.

Zinc can be added as zinc metal powder or in the form of a zinc compoundsuch as zinc oxide, zinc hydroxide, zinc carbonate, zinc acetate, zincformate, zinc chloride, zinc sulfate, zinc phosphate and the like.Preferably the zinc is added in the form of zinc oxide.

Alkaline earth metal can be introduced in the the form of an alkalineearth metal compound such as barium oxide, barium hydroxide, bariumcarbonate, barium sulfate, barium chloride, calcium oxide, calciumhydroxide, calcium carbonate, magnesium oxide, magnesium hydroxide,magnesium carbonate and the like including mixtures thereof. Preferablythe alkaline earth metal is a basic compound. The most preferredalkaline earth metal is barium and is introduced in the form of a basicbarium compound such as barium oxide, barium hydroxide, barium carbonateor mixtures thereof and the like. The most preferred form of barium isbarium carbonate.

The catalytic metals can be introduced separately or as a singlecompound or mixture of compounds. That is the catalyst can be introducedby adding copper or a copper compound, zinc or a zinc compound and analkaline earth metal base as three separate components. For example, thecatalyst will form by adding copper oxide, zinc oxide and bariumhydroxide separately to the reaction mixture.

Alternatively the copper, zinc and alkaline earth metal may beco-precipitated from a solution to form an intimate catalytic mixture.For example, copper nitrate, zinc nitrate and barium nitrate may bedissolved in aqueous nitric acid and precipitated as oxides and/orhydroxides by adding sodium hydroxide or carbonate to form an alkalinemixture. The co-precipitated mixture can be filtered to recover thesolid catalyst, dried and crushed to form a fine powder which can beadded to the reaction mixture as the catalyst.

Another way to form the catalyst is to impregnate a catalyst supportwith an aqueous solution of a water soluble salt of the catalytic metal.For example, an aqueous solution of copper nitrate, zinc nitrate andbarium nitrate may be formed and used to impregnate a catalyst supportsuch as alumina, silica, silica-alumina, magnesia, zirconia, kieselguhr,natural and synthetic zeolites and mixtures of the foregoing supports.The dry support is placed in the aqueous catalyst solution and allowedto absorb the solution. The remaining solution can be drained off orevaporated. The impregnated support is then dried and finally calcinedat an elevated temperature, for example 400°-800° C. in the presence ofair to form the active catalyst.

The atom ratio of copper to zinc to alkaline earth metal can varywidely. A useful range of catalytic metal is 10-100 copper: 10-100 zinc:0.02-40 alkaline earth metal. More preferably the atom ratio is 10-30copper: 10-30 zinc: 0.1-10 alkaline earth metal and most preferablyabout 20:20:1.

The amount of catalyst in the reaction mixture should be a catalyticamount. This means an amount which will catalyze the reaction of thealcohol and amine to alkylate the amine. The amount of catalyst isexpressed in terms of weight percent total catalytic metal based on theweight of the reaction mixture. A useful range of catalyst is about0.001-25 weight percent. A more preferred amount of catalyst is 0.05-7weight percent and a most preferred amount of catalyst is 1-5 weightpercent.

Previous catalysts containing copper that have been used to catalyze thereaction of amines with alcohol suffered from the problem that thecopper tends to dissolve in the reaction system and deposit throughoutthe reactor. This is readily apparent from the blue color of thereaction mixture. Surprisingly, it has been found that in the presentcatalyst system the copper does not appear to dissolve as shown by thelack of blue color in the liquid phase.

The catalyst can be recovered at the completion of the reaction bysettling and/or filtration. Filtration is improved by including an inertfilter aid such as Celite diatomaceous earth in the reaction mixture.Optionally the catalyst may be supported as previously described whichmakes separation much easier. The recovered catalyst can be recycledwithout further treatment and without noticeable loss of activity. Ifdesired the catalyst may be dried prior to recycle.

The process can be used to alkylate the nitrogen atom of any primary orsecondary amine. Examples of primary amines include methylamine,ethylamine, 1-propylamine, isobutylamine, 1-butylamine and the like.Preferred monoalkylamines are those in which the alkyl group containsabout 1-8 carbon atoms and more preferably 1-4 carbon atoms, especiallymethylamine.

Examples of secondary amines include dimethylamine, diethylamine,di-n-butyl amine, didecylamine, di(2-ethyldecyl)amine, dioctadecylamine,methyl dodecylamine, methyl eicosylamine, methyl docosylamine, methyltriacontylamine, isobutyl 2-ethylhexyl amine, n-butyl hexadecylamine,ethyl nonylamine, ethyl tetradecylamine, methyl cyclohexylamine, ethylcyclohexylamine, piperazine, piperidine, N-methyl aniline, N,N'-dimethylphenylene diamine and the like. The preferred secondary amines are thedi-lower alkylamines such as the di-C₁₋₄ alkylamines. The most preferredsecondary amines are di-C₁₋₂ alkylamines, especially dimethylamine("DMA").

Any alcohol containing 1 to about 30 carbon atoms can be used.Representative examples of these alcohols include methanol, ethanol,isopropanol, n-propanol, isobutanol, n-butanol, 2-ethyl hexanol,n-octanol, n-decanol, n-dodecanol, 2-ethyldecyl alcohol, n-tetradecanol,n-hexadecanol, n-octadecanol, 2-ethylhexadecyl alcohol, n-eicosanol,n-docosanol, 2-ethyleicosyl alcohol, n-tetracosanol, n-triacontanol andthe like.

The most useful alcohols are the C₈₋₂₂ mainly straight chain primaryalcohols. By "mainly" is meant at least 80 mole percent.

The reaction is preferably conducted in the presence of hydrogen duringat least a portion of the reaction. As mentioned earlier the hydrogencan be sparged into the reaction liquid phase together with the di-loweralkylamine (e.g., dimethylamine). The amount or rate of hydrogen spargedoes not appear to be critical and indeed the alkylation will proceedwithout hydrogen sparge albeit at a slower rate. A useful hydrogensparge rate is 0.001-1000 moles of hydrogen per hour per mole ofalcohol.

The hydrogen sparge can be used intermittently or continuously duringthe alkylation. The hydrogen can be diluted with an inert gas such asnitrogen. In one embodiment, hydrogen or a mixture of hydrogen andnitrogen are injected at the start of the reaction to activate thecatalyst and then the hydrogen stopped while the nitrogen sparge isstarted or continued to assist in water removal. If the reaction ratedecreases additional hydrogen can be added to the di-lower alkylaminesparge either continuously or periodically to re-activate the catalyst.

An especially preferred embodiment of the invention is a process formaking C₈₋₂₂ alkyl dimethylamine, said process comprising,

(A) mixing a catalyst consisting essentially of a copper oxide, zincoxide and an alkaline earth metal base with a C₈₋₂₂ primary mainlystraight chain alcohol

(B) contacting the mixture of alcohol and catalyst with hydrogen whileheating to a reaction temperature of about 180°-250° C.

(C) adding dimethylamine to the mixture of alcohol and catalyst while atsaid reaction temperature in an amount sufficient to convert at least 95percent of said alcohol to C₈₋₂₂ alkyl dimethylamine and

(D) recovering said C₈₋₂₂ alkyl dimethylamine.

Another especially preferred embodiment of the invention is a processfor making a di-(C₈₋₂₂ alkyl) methylamine, said process comprising:

(A) mixing a catalyst consisting essentially of a copper oxide, zincoxide and an alkaline earth metal base with a C₈₋₂₂ primary mainlystraight chain alcohol

(B) contacting the mixture of alcohol and catalyst with hydrogen whileheating to a reaction temperature of about 180°-250° C.

(C) adding methylamine to the mixture of alcohol and catalyst while atsaid reaction temperature in an amount sufficient to convert at least 95percent of said alcohol to di-(C₈₋₂₂ alkyl) methylamine and

(D) recovering said di(C₈₋₂₂ alkyl) methylamine.

In these especially preferred embodiments the catalyst is mixed with thealcohol before the catalyst contacts the amine. The alcohol catalystmixture is then heated rapidly to reaction temperature, about 180°-250°C., while contacting the mixture with hydrogen. This serves to activatethe catalyst. Once in this activated state the amine reactant can beadded without degrading the activity of the catalyst. Contact of thecatalyst with amine prior to hydrogen activation has been observed tosharply curtail the reaction rate.

In an optional mode of operation the catalyst can be preactivated duringmanufacture and then added to the alcohol. The alcohol can be pre-heatedto reaction temperature prior to catalyst addition or post-heatedrapidly to reaction temperature. Amine feed is then commenced preferablewith at least some hydrogen to maintain catalyst activity.

The following examples serve to show how the process is carried out andthe results which are achieved.

EXAMPLE 1

In a reaction vessel was placed 100 grams of commercial graden-dodecanol (EPAL®-12 alcohol, Ethyl Corporation), 1.0 grams CuO powder,1.0 grams ZnO powder and 0.2 grams Ba(OH)₂ ·8H₂ O. The vessel was thenpurged by sparging nitrogen into the liquid phase and allowing theexcess nitrogen to vent. The reaction mixture was heated to 100° C.while stirring. Nitrogen sparge was stopped and hydrogen sparging wasstarted at 0.8 SCFH. Heating was continued to 200° C. at whichtemperature hydrogen sparge was reduced to 0.4 SCFH and dimethylamine(DMA) feed in a gas state was started. Over a 4-hour period, 115 gramsof DMA was fed at 202°-205° C. The vent gas (mainly hydrogen, unreactedDMA and volatiles) was passed through a condenser and condensatecollected in a Dean Stark water trap forming a 2-phase condensate. Thelower aqueous phase was removed and weighed 9.6 grams. After standingovernight, the mixture was again heated to 115° C. with nitrogen spargeand then nitrogen was shut off and hydrogen sparge commenced at 0.8SCFH. Heating was continued up to 200° C. and DMA vapor feed againstarted while dropping the hydrogen sparge to 0.4 SCFH. DMA feed wascontinued for 3 hours to feed an additional 85 grams of DMA whilepassing the vent gas through the water trap. An additional 1.6 grams ofaqueous layer was removed. The reaction mixture was cooled and filteredto remove the catalyst giving 75.1 grams of filtrate. The filtrate wasanalyzed by gas chromatography (GC) as follows:

    ______________________________________                                                        Area Percent                                                  ______________________________________                                        dodecyl dimethylamine                                                                           93.5                                                        dialkylmethylamine                                                                              3.2                                                         dodecanol         1.4                                                         ______________________________________                                    

EXAMPLES 2-4

The above procedure was repeated with the following modifications:

    ______________________________________                                                      Reaction  Reaction                                              Example       Temp (°C.)                                                                       Time (Hrs)                                            ______________________________________                                        2             230       4                                                     3             206       7                                                     4             200       8                                                     ______________________________________                                    

The product analyzed by GC (area percent) as follows:

    ______________________________________                                                      Example                                                                       2        3      4                                               ______________________________________                                        dodecyl dimethylamine                                                                         86.6       93.8   95.1                                        dialkylmethylamine                                                                            10.9       3.2    2.7                                         dodecanol       0.2        1.2    0.3                                         ______________________________________                                    

EXAMPLES 5-7

These examples show the process conducted with catalyst recycle. In eachcase the reactor charge was about 100 grams of n-dodecanol pluscatalyst. Reaction time was 8 hours at 200°-204° C. with 140 grams ofDMA feed (145 grams in Example 7) and hydrogen sparge at 0.4 SCFH. InExample 5 the catalyst charge was 1.0 gram ZnO, 1.0 gram CuO and 0.2gram Ba(OH)₂ ·8H₂ O.

In Example 6 the catalyst was 2.8 grams of filtered wet catalystrecovered from Example 5 plus 0.22 grams of fresh CuO-ZnO-Ba(OH)₂ ·8H₂ Ocatalyst in the same metal ratio as before.

In Example 7 the catalyst was 1.7 grams of recovered wet catalyst fromExample 6 and 0.22 grams of fresh CuO-ZnO-Ba(OH)₂ ·8H₂ O catalyst.

The following table shows the result of the recycle runs in area percentby GC.

    ______________________________________                                                      Example                                                                       5        6      7                                               ______________________________________                                        dodecyl dimethylamine                                                                         95.7       96.4   96.2                                        dialkylmethylamine                                                                            2.6        2.2    2.4                                         dodecanol       0.2        0.2    0.2                                         ______________________________________                                    

Little, if any, copper migration was observed in the run. The examplesdemonstrate that the process is capable of giving very high conversionof alcohol to amines.

EXAMPLE 8

In a 2 liter reaction vessel was placed 940 grams of a commercial graden-octadecanol(EPAL® 18 Alcohol, Ethyl Corporation), 10 grams of CuOpowder, 10 grams of ZnO powder and 2.0 grams of Ba(OH)₂ ·8H₂ O. Thevessel was sparged with nitrogen and heated with stirring to 140° C.Nitrogen sparge was stopped and hydrogen sparge was commenced at 0.46SCFH. Heating was continued and at 202° C. gaseous DMA was injected intothe liquid phase together with the hydrogen sparge. Over a 10-hourperiod, 550 grams of DMA was fed at 216° C. Volatiles removed in thevent gas were condensed. The reaction mixture was cooled and filtered toremove the catalyst. The product analyzed by GC as follows:

    ______________________________________                                                         Area Percent                                                 ______________________________________                                        octadecenyl dimethylamine                                                                        2.1                                                        octadecyl dimethylamine                                                                          85.1                                                       dioctadecyl methylamine                                                                          7.5                                                        octadecanol        0.28                                                       other              5.0                                                        ______________________________________                                    

EXAMPLES 9-13

A series of tests was conducted without hydrogen sparge to measure therelative activity of several catalyst systems without attempting toachieve maximum conversion. In these tests an autoclave was charged with100 grams of n-dodecanol and the indicated catalyst. Then 30 grams ofDMA was added and the autoclave sealed and pressurized to 100 psig withhydrogen. Over a 30-minute period the autoclave was heated to 210° C.and then stirred at 210° C. for exactly four hours. The reaction mixturewas then sampled and analyzed by GC. The results of Examples 9-13 aretabulated in the following table:

    ______________________________________                                                       Product (Area %)                                                                            n-dodecyl                                                                             n-dodecyl                                Ex-                  n-dode- dimethyl                                                                              methyl                                   ample Catalyst       canol   amine   amine                                    ______________________________________                                        9     1.0 g CuO          80.8  18.1    1.1                                          0.1 g Cr.sub.2 O.sub.3                                                                    1                                                                 0.1 g BaO                                                               10    1.0 g CuO          66.9  29.7    2.3                                          0.1 g Cr.sub.2 O.sub.3                                                        0.1 g BaO   1                                                                 1.0 g ZnO.sup.2                                                         11    1.0 g CuO          73.3  22.7    1.1                                          0.1 g Cr.sub.2 O.sub.3                                                        0.1 g BaO   2                                                                 1.0 g ZnO                                                               12    1.0 g CuO          93.3  6.0     trace                                        1.0 g ZnO   1                                                                 0.1 g Ba(OH).sub.2                                                      13    1.0 g ZnO          99.5  trace   --                                     ______________________________________                                         1. Each added separately                                                      2. Recycled from Example 10                                              

Comparing Examples 9 and 10 it can be seen that zinc oxide significantlyincreases the conversion to n-dodecyl dimethylamines from 18.1 percentup to 29.7 percent. Comparing Examples 10 and 12 it can be seen that theinclusion of Cr₂ O₃ with the CuO-ZnO-Ba(OH)₂ increases the conversion ton-dodecyl dimethylamine while at the same time introducing a smallamount of n-dodecyl methylamine which could be detrimental in someinstances since it is difficult to separate this coproduct fromn-dodecyl dimethylamine. However, where the presence of this coproductis not detrimental the further inclusion of Cr₂ O₃ promoter isadvantageous when making a C₈₋₂₂ alkyl dimethylamine. Similar promotereffects are obtained by including cobalt and/or nickel preferably in theform of an oxide.

The following example shows the process conducted with magnesiumcarbonate as the alkaline earth metal base.

EXAMPLE 14

In a reactor was placed 100 g of a mixture of primary C₁₆ plus C₁₈alcohols and a catalyst consisting of 1.0 g copper oxide, 1.0 g zincoxide and 0.2 g magnesium carbonate. DMA and hydrogen were sparged intothe vigorously stirred liquid phase 210° C. The total amount of DMA fedwas 140% of theoretical. Samples were removed every hour and analyzed asfollows:

    ______________________________________                                                     Composition (Area %).sup.2                                       Reaction Time (hrs)                                                                          Alcohol  Alkyl Dimethylamine.sup.1                             ______________________________________                                        1              89.3     1.8                                                   2              40.4     49.6                                                  3              8.4      82.7                                                  4              0.9      88.8                                                  ______________________________________                                         1. C.sub.16-18 alkyl dimethylamine.                                           2. Balance is mixture of byproducts.                                     

EXAMPLE 15

This alkylation was conducted using barium carbonate as the alkalineearth metal base.

In a reactor was placed 1977 g mixed primary C₁₆ -C₁₈ alcohol, 25 gcopper oxide, 25 g zinc oxide and 5 g barium carbonate. DMA and hydrogenwere sparged into the liquid phase over a 7.5-hour period at 210° C.Total DMA feed was 197% of theory.

The following table gives the results.

    ______________________________________                                                     Composition (Area %)                                             Reaction Time (hrs)                                                                          Alcohol  Alkyl Dimethylamine                                   ______________________________________                                        1              63.6     22.9                                                  2              46.2     42.3                                                  3              26.6     59.1                                                  4              18.1     71.3                                                  5              8.5      78.6                                                  6              3.5      81.6                                                  7.5            0.8      81.3                                                  ______________________________________                                    

EXAMPLE 16

This reaction was conducted using the catalyst recovered from Example 15by filtration and without hydrogen sparge.

In a reactor was placed 2030 g mixed C₁₆₋₁₈ primary alcohols and thecatalyst recovered from Example 15. The reactor was sealed and DMAsparged into the liquid phase for 10 hours at 210° C. Total DMA feed was111% of theory. The following table shows the composition of thealkylation mixture during the reaction.

    ______________________________________                                                     Composition (Area %)                                             Reaction Time (hrs)                                                                          Alcohol  Alkyl Dimethylamine                                   ______________________________________                                        1              70.4     20.2                                                  2              53.8     36.4                                                  3              43.0     46.6                                                  4              30.9     58.6                                                  5              21.4     63.9                                                  8              8.7      74.9                                                  9              3.5      78.1                                                  10             1.9      79.3                                                  ______________________________________                                    

These results show that it is not necessary to sparge hydrogen throughthe reaction mixture during the alkylation. The rate, however, issomewhat lower without the hydrogen sparge.

The following example shows the process conducted with a calcium base.

EXAMPLE 17

In a reaction vessel was placed 100 rams of commercial grade n-dodecanol(EPAL®-12 alcohol, Ethyl Corporation), 2.2 grams of mixed CuO/ZnO/CaCO₃powders (weight ratio of CuO/ZnO/CaCO₃ =5/5/1). The vessel was thenpurged by sparging nitrogen into the liquid phase and allowing theexcess nitrogen to vent. The reaction mixture was heated to 103° C.while stirring. Nitrogen sparge was stopped and hydrogen sparging wasstarted at 0.8 SCFH. Heating was continued to 206° C. at whichtemperature hydrogen sparge was reduced to 0.4 SCFH and DMA vapor feedwas started. Over a 7-hour period, 100 grams of DMA was fed at 206°-216°C. The vent gas (mainly hydrogen, unreacted DMA and volatiles) waspassed through a condenser and condensate collected in a clean starktrap forming a 2-phase condensate. The lower aqueous phase collected was15.5 milliliters. The reaction mixture was cooled and filtered to removethe catalyst. The filtrate was analyzed by GC as follows:

    ______________________________________                                                        Area Percent                                                  ______________________________________                                        dodecyl dimethylamine                                                                           93.9                                                        dialkylmethylamine                                                                              3.6                                                         dodecanol         1.0                                                         ______________________________________                                    

The following Examples 18-36 show the process conducted with amono-lower alkylamine.

EXAMPLE 18

In a reaction vessel was placed 50 grams of commercial grade 1-decanol,0.48 grams of copper oxide, 0.01 grams of zinc oxide and 0.01 grams ofbarium hydroxide. The mixture was sparged with nitrogen for 15 minutesand then with hydrogen. The mixture was heated to 200° C. and thehydrogen sparge replaced with combined hydrogen and monomethylamine(MMA) sparge at a rate of 5 cc/min each. This was continued for 7 hours.At 4 hours and at 7 hours the reaction mixture was analyzed by GC withthe following results:

    ______________________________________                                                          4 Hrs 7 Hrs                                                 ______________________________________                                        1-decanol           3.4%    0%                                                decyl methylamine   9.2%    15.5%                                             decyl dimethylamine 0.2%    0.4%                                              didecyl methylamine 80.5%   81.5%                                             didecyl amine       0.2%    0.6%                                              decyl decanoate     1.6%    1.5%                                              decyl decenyl methylamine                                                                         2.7%    0.7%                                              tridecylamine       0.3%    0.3%                                              ______________________________________                                    

The analyses shows that the yield of didecyl methylamine had plateauedbecause all of the 1-decanol had been consumed. Calculation showed thatan additional 8.55 grams of 1-decanol was needed to convert the decylmethylamine to didecyl methylamine. This alcohol was added and themixture reacted at 200° C. for about hours with hydrogen and nitrogensparge (5 cc/min each) but without additional MMA sparge. The mixtureanalyzed at the end of this additional reaction period as follows:

    ______________________________________                                        decyl dimethylamine                                                                             0.4%                                                        didecyl methylamine                                                                             96.2%                                                       decyl decanoate   1.5%                                                        ______________________________________                                    

EXAMPLE 19

In a 100 ml glass reaction vessel was placed 50 grams commercial gradeoctadecanol, 0.48 grams copper oxide, 0.01 grams zinc oxide and 0.01grams barium hydroxide (anhydrous). This was sparged with N₂ for 15minutes and then with H₂ at 10 cc/min while heating to 200° C. for 4hours. Since octadecanol is a solid at room temperature hot water wasused in the vent gas condenser so water was not condensed. The spargewas stopped and the reaction mixture analyzed by GC:

    ______________________________________                                        octadecanol        0.3%                                                       dioctadecyl methylamine                                                                          96.7%                                                      unknown            1.8%.sup.1                                                 ______________________________________                                         .sup.1 Tentatively identified as either dioctadecylamine or octadecyl         octadecanoate.                                                           

This reaction came out almost perfect without the need to add morealcohol or MMA and conduct a second stage reaction.

The catalyst can be recovered by filtration following each operation andrecycled to the next operation. An inert filter aid such as diatomaceousearth can be included when using an unsupported catalyst to make thefiltration easier. The entire catalyst and filter aid can be recycled tothe next operation.

The process has been described as a batch operation. It can be convertedto a continuous process by placing the catalyst, preferably on asupport, in a tubular reactor of sufficient volume to give the requiredcatalyst contact time at the desired reaction rate and passing thealcohol down through the catalyst bed while passing a countercurrentflow of hydrogen and lower alkylamine up through the catalyst bed whilemaintaining the catalyst at reaction temperature.

A series of experiments was conducted in a similar manner to makedidecyl methylamine from n-decanol and MMA. The procedure used was toflush the round bottom glass reaction flask with nitrogen and charge 100g alcohol and catalyst. The flask had a stirrer set to run at 200 rpmand a 5° C. water condenser over a Dean Stark water trap. A sparge tubeextended into the liquid phase. The system was first sparged withnitrogen for 15 minutes and then hydrogen at 1 SCFH with nitrogen spargestopped. The alcohol-catalyst mixture was heated at 200° C. over 30 min.while continuing hydrogen sparge. Then MMA (1 SCFH) was mixed with thehydrogen sparge. Any water collected in the Dean Stark separator wasremoved. The composition of the flask was periodically monitored by G.C.The following table gives modifications made during the series andresults:

    ______________________________________                                               Catalyst       Reaction  Conver-                                       Ex.    (g)            Time (hrs.)                                                                             sion.sup.2                                                                           Yield.sup.3                            ______________________________________                                        20.sup.1   CuO          0.48  1       6.8    58.4                                        ZnO          0.01  4       49.4   92.7                                        Ba(OH).sub.2 0.01  7       73.6   93.6                             21         Copper.sup.4 1.0   2       88.9   84.0                                        Zinc.sup.4   1.0   4       93.0   87.1                                        Ba(OH).sub.2 0.2   6       95.8   79.9                             22.sup.5   CuO          6.1   2       70.6   87.3                                        ZnO          6.1   4       91.6   86.9                                        Ba(OH).sub.2 2.0   6       95.3   85.7                             23         CuO          1.0   1       17.7   77.7                                        ZnO          1.0   3       41.9   90.8                                        BaCl.sub.2   0.25  6       60.4   90.1                             24         CuO          1.0   --      --     --                                          ZnO          1.0   6       84.1   87.9                                        BaSO.sub.4   0.24  --      --     --                               25.sup.6   CuO          1.0   2       32.6   83.0                                        ZnO          1.0   3       50.5   84.2                                        BaCO.sub.3   0.2   4       57.2   77.8                             26         CuO          1.0   2       77.0   85.7                                        ZnO          1.0   4       97.7   85.0                                        MgCO.sub.3   0.49  6       99.4   83.1                             27         CuO          1.0   1       49.3   89.4                                        ZnO          1.0   3       88.1   86.6                                        BaCO.sub.3   0.2   6       100.0  83.0                             28         CuO          1.0   --      --     --                                          ZnO          1.0   4       82.5   90.3                                        MgO          0.25  6       94.4   88.9                             29         CuO          1.0   2       59.0   89.2                                        ZnO          1.0   4       86.9   89.2                                        Calcium.sup.4                                                                              0.14  6       96.6   89.4                             30         CuO          1.0   2       51.0   86.8                                        ZnO          1.0   4       73.8   89.9                                        SrCO.sub.3   0.24  6       89.4   87.9                             31         CuO          1.0   --      --     --                                          ZnO          1.0   --      --     --                                          BaCO.sub.3   0.2   6       93.5   92.4                             32         CuO          1.0   --      --     --                                          ZnO          1.0   --      --     --                                          BaCO.sub.3   0.2   6       93.6   91.6                             33         CuO          1.0   --      --     --                                          ZnO          1.0   --      --     --                                          BaCO.sub.3   0.2   6       93.7   92.0                             ______________________________________                                         1. 50 g ndecanol, no H.sub.2 sparge.                                          2. "Conversion" is the percent of the alcohol consumed.                       3. "Yield" is the percent of the "consumed" alcohol that formed didecyl       methylamine, monodecyl methylamine or unsaturated didecyl methylamine.        4. As the metal powder.                                                       5. 610.3 g ndecanol, MMA sparge at 2 SCFH.                                    6. MMA sparge at 5 cfh.                                                  

A series of experiments was conducted to show the detrimental affect ofcontacting the catalyst with amine below reaction temperature. Theprocedure was the same as used in Examples 20-33. The catalyst in eachcase was 1 g CuO, 1 g ZnO, 0.2 g BaCO₃.

In Example 34 a hydrogen sparge of 1 SCFH was maintained while heatingthe n-decanol catalyst mixture to 200° C. over 30 minutes. Then thesparge was changed to 1 SCFH hydrogen plus 1 SCFH MMA for a 6 hourreaction at 200° C.

In Example 35 the hydrogen sparge during heat-up to reaction temperaturewas replaced by 1 SCFH MMA sparge.

In Example 36 the hydrogen sparge during heat-up was changed to 0.5 SCFHhydrogen plus 0.5 SCFH MMA.

The following table shows the results after a 6 hour reaction period.

    ______________________________________                                        Example        Conversion                                                                              Yield                                                ______________________________________                                        34             93.6      91.6                                                 35             53.0      92.8                                                 36             64.2      94.0                                                 ______________________________________                                    

Example 34 shows a typical baseline run with this catalyst. Example 35shows the sharp drop in conversion caused by contact of the catalystwith amine during heat-up to reaction temperature. Example 36 shows thatinclusion of hydrogen sparge with the premature amine contact can lessenthe detrimental effect but does not entirely counteract the affect.

One of the most surprising features of the invention is that thecatalytic components can be added separately and need not be added as acomposite. It is not apparent how each component can cooperate with theother components to give the improved catalytic properties. This isespecially applicable to the zinc or zinc oxide. Zinc oxide itself haslittle if any catalytic effect on the alkylation of amines by alcohols.This can be seen in above Example 13. However when zinc oxide is addedto a copper-containing catalyst it greatly improves the effectiveness ofthe copper-containing catalyst. The zinc oxide can be mixed with thecopper-containing catalyst and the mixture added to the reaction vesselor the zinc oxide can be separately added to the reaction vessel. Forexample copper oxide can be added to a reaction vessel containing thealcohol alkylating agent and the zinc oxide and barium hydroxide orcarbonate added separately to the same reaction vessel. Alternativelycopper oxide can be mixed with zinc oxide and barium hydroxide orcarbonate and the mixture added to the reaction vessel. In another modeof operation the copper, zinc and barium may be impregnated on asuitable support either all at once from a common solution or separatelyfrom different solutions. Alternatively the copper, zinc and alkalineearth metal compounds (e.g., nitrates, acetates) may be dissolved in anaqueous solution and then mixed with base (e.g., Na₂ CO₃, NaOH) toco-precipitate the catalyst.

From the above it can be seen that a further embodiment of the inventionis an improvement in a process for making a trialkylamine by reacting analkylamine selected from mono- and di-lower alkylamines in the liquidphase with a C₈₋₂₂ primary alcohol or mixtures thereof in the presenceof a copper-containing catalyst. The improvement comprises adding zincoxide to the reaction mixture. Results are improved still further byincluding an alkaline earth metal base, especially barium oxide,hydroxide carbonate or mixtures thereof in the reaction mixture. Theimproved process is preferably conducted in contact with hydrogen atleast part time.

Another embodiment of the invention is the catalyst used in the process.This is a non-colloidal catalyst consisting essentially of supported orunsupported copper oxide, zinc oxide and an alkaline earth metal base.The base can be a barium, calcium or magnesium base such as an oxide,hydroxide or carbonate. The preferred alkaline earth metal base isbarium hydroxide or barium carbonate. The atom ratio ofcopper:zinc:alkaline earth metal is preferably 10-30 copper:10-100zinc:0.1-10 alkaline earth metal. A more preferred ratio is 10-30copper:10-30 zinc:0.1-10 alkaline earth metal.

The preferred alcohol alkylating agents are the C₈₋₂₂ mainlystraight-chain alpha-alcohols. By "mainly straight-chain" is meant thatthe alcohol is at least 80 mole percent straight-chain. One of thesurprising features of the reaction that has been observed is that if aminor amount of a branched-chain alcohol is present in the alcoholreactant, it is apparently converted to straight-chain alcohol. This isbased on the observation that the alkylation of dimethylamine with acommercial dodecanol which contained about 5 mole percent of branchedalcohol yielded dodecyl dimethylamine in which the dodecyl groups wereall straight-chain. The residual alcohol was analyzed by GC andbranched-chain alcohol was not detected in the residue. Spiking theresidue with a trace of branched-chain dodecanol and further analysisverified that the analytical method was capable of detectingbranched-chain alcohol. The fate of the branched-chain alcohol is notknown with certainty but it appears that it may be isomerized to formstraight-chain alcohol.

We claim:
 1. A process for making trialkylamine by reacting a lower alkylamine selected from mono- and di-lower alkylamines with a C₈₋₂₂ primary alcohol in the liquid phase at a temperature of 150°-275° C. and in contact with a recyclable catalyst consisting essentially of copper and/or copper oxide, zinc and/or zinc oxide and an alkaline earth metal base, said catalyst being in a solid form and easily separatable from the reaction product by filtration.
 2. A process of claim 1 conducted in contact with hydrogen during at least a portion of the reaction period.
 3. A process of claim 2 wherein said alkaline earth metal is selected from the group consisting of barium, calcium and magnesium.
 4. A process of claim 3 wherein said lower alkylamine is dimethylamine.
 5. A process of claim 4 wherein said alkaline earth metal base is selected from the group consisting of barium oxide, barium hydroxide, barium carbonate, calcium oxide, calcium hydroxide, calcium carbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate and mixtures thereof.
 6. A process of claim 5 conducted at 190°-230° C. while removing water formed in the reaction.
 7. A process of claim 6 wherein said catalyst consists initially of (a) copper and/or copper oxide, (b) zinc and/or zinc oxide and (c) barium oxide, hydroxide or carbonate or mixtures thereof.
 8. A process of claim 7 wherein said catalyst consists initially of copper oxide, zinc oxide and barium carbonate.
 9. A process of claim 8 wherein said primary alcohol contains in the range of 10-20 carbon atoms.
 10. A process of claim 9 wherein said primary alcohol is n-dodecanol, n-tetradecanol, n-hexadecanol, n-octadecanol or mixtures thereof.
 11. A process of claim 4 comprising reacting dimethylamine with a C₈₋₂₂ primary alcohol in the liquid phase and in the presence of hydrogen at least a portion of the time at a temperature of 180°-250° C. and in contact with a copper oxide-zinc oxide-barium base catalyst.
 12. A process of claim 11 wherein said barium base is barium hydroxide.
 13. A process of claim 11 wherein said barium base is barium carbonate.
 14. A process of claim 13 conducted at a temperature of about 190-230° C. while removing water formed in the reaction.
 15. A process of claim 14 wherein said catalyst is unsupported.
 16. A process of claim 14 wherein said catalyst is supported on a catalyst support.
 17. A process of claim 14 wherein said alcohol is mainly straight-chain and contains about 10-18 carbon atoms.
 18. A process of claim 3 wherein said lower alkylamine is monomethylamine.
 19. A process of claim 18 wherein said alkaline earth metal base is selected from the group consisting of barium oxide, barium hydroxide, barium carbonate, calcium oxide, calcium hydroxide, calcium carbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate and mixtures thereof.
 20. A process of claim 19 conducted at 190°-230° C. while removing water formed in the reaction.
 21. A process of claim 20 wherein said catalyst consists initially of (a) copper and/or copper oxide, (b) zinc and/or zinc oxide and (c) barium oxide, hydroxide or carbonate or mixtures thereof.
 22. A process of claim 21 wherein said catalyst consists initially of copper oxide, zinc oxide and barium carbonate.
 23. A process of claim 22 wherein said primary alcohol contains in the range of 10-20 carbon atoms.
 24. A process of claim 23 wherein said primary alcohol is n-octanol, n-decanol, n-dodecanol or mixtures thereof.
 25. A process of claim 18 comprising reacting methylamine with a C₈₋₂₂ primary alcohol in the liquid phase and in the presence of hydrogen at least a portion of the time at a temperature of 180°-250° C. and in contact with a copper oxide-zinc oxide-barium base catalyst.
 26. A process of claim 25 wherein said barium base is barium hydroxide.
 27. A process of claim 25 wherein said barium base is barium carbonate.
 28. A process of claim 27 conducted at a temperature of about 190°-230° C. while removing water formed in the reaction.
 29. A process of claim 28 wherein said catalyst is unsupported.
 30. A process of claim 28 wherein said catalyst is supported on a catalyst support.
 31. A process of claim 28 wherein said alcohol is mainly straight-chain and contains about 8-18 carbon atoms.
 32. In a process for making trialkylamines, said process comprising reacting an alkylamine selected from mono- and di-lower alkylamines in the liquid phase with a C₈₋₂₂ primary alcohol or mixtures thereof in the presence of a recyclable copper-containing catalyst and in contact with hydrogen during at least a portion of the reaction period, the improvement of adding zinc oxide to the reaction mixture.
 33. The process of claim 32 wherein the copper-containing catalyst is copper oxide.
 34. The process of claim 33 wherein said catalyst includes an alkaline earth metal base.
 35. The process of claim 34 wherein said alkaline earth metal base is barium oxide, barium hydroxide, barium carbonate or mixtures thereof.
 36. A process of claim 4 for making C₈₋₂₂ alkyl dimethylamine, said process comprising,(A) mixing a catalyst consisting essentially of a copper oxide, zinc oxide and an alkaline earth metal base with a C₈₋₂₂ primary mainly straight chain alcohol (B) contacting the mixture of alcohol and catalyst with hydrogen while heating to a reaction temperature of about 180°-250 C. (C) adding said dimethylamine to the mixture of alcohol and catalyst while at said reaction temperature in an amount sufficient to convert at least 95 percent of said alcohol to C₈₋₂₂ alkyl dimethylamine and (D) recovering said C₈₋₂₂ alkyl dimethylamine.
 37. A process of claim 36 wherein said alkaline earth metal base is a barium base.
 38. A process of claim 37 wherein said barium base is barium carbonate.
 39. A process of claim 18 for making a di-(C₈₋₂₂ alkyl) methylamine, said process comprising:(A) mixing a catalyst consisting essentially of a copper oxide, zinc oxide and an alkaline earth metal base with a C₈₋₂₂ primary mainly straight chain alcohol (B) contacting the mixture of alcohol and catalyst with hydrogen while heating to a reaction temperature of about 180°-250° C. (C) adding said monomethylamine to the mixture of alcohol and catalyst while at said reaction temperature in an amount sufficient to convert at least 95 percent of said alcohol to di-(C₈₋₂₂ alkyl) methylamine and (D) recovering said di-(C₈₋₂₂ alkyl) methylamine. 